Theory of the Heats of Formation of Transition-Metal Alloys

Abstract

A simple expression for the heat of formation $\Delta H$ of transition-metal alloys is derived with-in the tight-binding approximation that has the form $\Delta H=f\left(\overline{N}\right)\Delta N^2$, where $\overline{N}$ and $\Delta N$ are the average and difference in number of valence $d$ electrons, respectively. The prefactor $f\left(\overline{N}\right)$ is most negative for $\overline{N}$ lying near the middle of the series and it becomes positive towards the edges. The theory gives good agreement with Miedema's semiempirical values of $\Delta H$.